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Although discovery of the quickly spreading omicron variant has put governments on high alert, the U.S. population is much better protected against SARS-CoV-2 than it was before the pandemic, some experts say. 

The highly mutated variant — which was detected for the first time in the United States on Tuesday — may raise the number of breakthrough infections among the vaccinated, But current COVID-19 vaccines are expected to be at least somewhat protective against it. Furthermore, many people are now more immunologically prepared to handle the threat than ever.

Two years and millions of vaccinations administered since the start of the pandemic have likely helped to prime our immune systems with a kind of “memory” of the SARS-CoV-2 virus, reported Helen Branswell in the medical news outlet Stat. 

Storehouse of defenses

People have been vaccinated against, exposed to or weathered COVID-19 illness, for example, potentially building a storehouse of added defenses that can recognize and resist or neutralize the virus. One recent study, for example, found that SARS-CoV-2 reinfections were 90% less likely than a first infection to cause hospitalization or death. 

“It’s never like [being back at] square one,” Ali Ellebedy, an associate professor of pathology and immunology at Washington University School of Medicine in St. Louis, told Branswell. “The virus is going to not find it as easy compared to the situation in January 2020 or December 2019. It’s just completely different now.”

Omicron is no reason to “freak out,” but the booster vaccine rollout should go faster, vaccine maker Ugur Sahin told the Wall Street Journal. 

Sahin is the co-founder of BioNTech SE, who along with Pfizer Inc., developed one of the three COVID-19 vaccines approved for use in the United States. New variants such as omicron are more likely to break through the shot’s protective antibodies, which wane over time. But COVID-19 vaccines encourage the buildup of a longer-lasting form of protection called T-cells, he said.

“Our belief [that the vaccines work against omicron] is rooted in science: If a virus achieves immune escape, it achieves it against antibodies,” he said. “But there is the second level of immune response that protects from severe disease — the T-cells,” he added.

Another veteran vaccine scientist did not agree with this assessment. There is little evidence that in the absence of antibodies that T-cells will do the job, Stanley Plotkin, M.D., who helped develop the rubella vaccine, told the WSJ. But it does make sense that to keep itself alive and working, the SARS-CoV-2 virus would become more infectious but less deadly to humans over time, he said.

“It makes sense for the virus to want to infect as many people as possible without killing them,” Dr. Plotkin said.

First-known case

On Tuesday, the first-known case of the omicron variant to arrive in the United States was detected in California. It was found in a traveler who had returned from South Africa in late November, according to the Centers for Disease Control and Prevention.

“The individual had mild symptoms that are improving, is self-quarantining and has been since testing positive,” CDC reported. “All close contacts have been contacted and have tested negative.”